NASA Advances Nuclear Power Module Work for SR-1 Freedom

NASA has advanced contract work for the nuclear power module of Space Reactor-1 Freedom, a spacecraft planned to demonstrate nuclear electric propulsion beyond Earth orbit and deliver the SkyFall science payload to Mars. The agency says Sierra Lobo will provide the closed Brayton cycle power conversion system, integrated with a fission reactor designed by Idaho National Laboratory, ahead of a late 2028 launch. NASA report.

Program Status and Contract Actions

NASA says the SR-1 Freedom program has moved forward through mutually agreed contract actions with partners. The agency frames these actions as reducing technical risk, sustaining momentum toward the planned 2028 launch and improving collaboration. The work concerns the spacecraft's nuclear power module, a key element for the mission.

Steve Sinacore, SR-1 Freedom program director, said the actions keep the effort on track and support a foundation for the first fission-powered voyage beyond Earth orbit. NASA also says the technology is intended to be extensible to future space nuclear work. The source describes progress on the module, not completion.

Related coverage: related Space reporting.

Module Architecture and Partner Roles

The nuclear power module sits at the end of the spacecraft's boom. It combines a reactor that generates heat through nuclear fission with a power conversion system that turns that heat into electricity. That electricity is meant to power spacecraft systems and electric propulsion.

Sierra Lobo Inc. will provide the closed Brayton cycle power conversion system. The work will be conducted under the Space Flight Systems Development and Operations Contract III, awarded in 2024, to support spaceflight hardware design, development, testing and operations at NASA's Glenn Research Center in Cleveland. It will be integrated with the fission reactor.

Related coverage: related Space reporting.

Safety Reviews and Reactor Activation Limits

The fission reactor is being designed and developed by the Department of Energy's Idaho National Laboratory. Integration of that reactor with Sierra Lobo's conversion system is intended to complete the nuclear power module. NASA describes the module as central to the nuclear electric propulsion demonstration.

NASA and DOE say they incorporate safety standards throughout design and development. The source lists interagency safety reviews, continuous oversight by a NASA chief safety officer, regulatory compliance and a safety design process focused on hazards, failure tolerance and nuclear safety. The reactor portion will remain inactive until the spacecraft leaves Earth orbit.

Related coverage: related Space reporting.

Mission Scope and Exploration Aims

The mission is planned to launch in late 2028 and deliver the SkyFall science mission. That payload is described as a team of three Mars helicopters evolved from the Ingenuity design. NASA says the helicopters are intended to collect scientific data, demonstrate exploration zones and identify potential water sources.

NASA positions SR-1 Freedom as a step toward deep space exploration and next-generation fission-powered systems. The agency says such systems are designed to keep a Moon Base operating through periods of darkness and in locations where solar power alone is not sufficient. These are stated mission aims, not demonstrated results.

Related coverage: related Space reporting.

What This Means for Practitioners

For research planners, the first question is whether the contract actions reduce technical risk enough to support the planned 2028 launch, and what evidence NASA and partners will publish on module integration. If the reactor remains inactive until orbit departure, what testing and review records will be available to independent evaluators?

For commercial or agency buyers considering fission-powered systems, the assessment depends on whether the closed Brayton cycle conversion system meets integration requirements with the Idaho National Laboratory reactor, and whether safety reviews address failure tolerance. If the technology is meant to be extensible, what criteria would show readiness beyond a single demonstration?